High-voltage ozone-free electrostatic air filter

ABSTRACT

An electrostatic air filter having an air duct defined in part by opposed walls over which liquid flows continuously. An electrode is suspended between the aforesaid walls and cooperates therewith to purify the air flowing through the duct. The electrode is connected to a high voltage source and is preferably divided into two parts, one of which is designed to produce a strong ionization with spray discharge.

- ted States Patent 1191 I Ebert [451 July 10, 1973 [54] HIGH-VOLTAGE ()ZONE4FREE 1,605,648 11/1926 Cooke 55/ 138 ELECTROSTATIC AIR FILTER 3,124,437 3/1964 Lagarias 1 55/ 13 3,238,702 3/1966 De Seversky... 55/152 Inventor: Paul Ebert, Hunhngue, France 3,672,126 6/1972 Goettle 55/126 [73] Assignee: Aeropur, A.G., Zug, Switzerland FOREIGN PATENTS OR APPLICATIONS- 22 fl Dem 23 1970 529,210 9/1921 France 55/134 858,692 12/1952 Germany 55/146 [21] Appl. No.: 101,050 Primary Examiner-Hemard Nozick 52 us. (:1 55/118, 55/123, 55/124, AmmeY-Chmkk Birch, Samuels & Gauthier 55/134, 55/138, 55/152, 55/279, 55/387, 55/1510. 36, 98/115 K 1 1 ABSTRACT [51] Int. Cl. 1103c 3/38 An electrostatic air filter having an air duct defined in [58] Field of Search 55/2, 387, 6l3, part by opposed walls over which liquid flows continu- 55/102, 108, 107, 117, 119, 118, 120, 122, ously. An electrode is suspended between the aforesaid 124, 123, 126, 129, 134, 135, 136-138, 146, walls and cooperates therewith to purify the air flowing 152, 153, 279, DlG. 36; 98/1 15 K through the duct. The electrode is connected to a high voltage source and is preferably divided into-two parts, [56] References Cited one of which is designed to produce a strong ionization UNITED STATES PATENTS with p y discharge- 804,291 11/1905 Wood 55/150 6 Claims, 6 Drawing Figures PATENTED mam:

attorneys HIGH-VOLTAGE OZONE-FREE ELECTROSTATIC AIR FILTER DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for pu rifying air in homes, offices, factories, hospitals, etc. Its purpose is the removal of dust and odors and the restoration of breathing air with simultaneous disinfection and moistening.

The present invention differs from conventional devices of the type generally referred to above in that it operates with high voltages previously not employed in air-conditioning equipment. This is accomplished without injury to health as a result of ozone being produced by the ionization corona.

With the present invention, depending on type of use, the voltages are 20 100 KV direct current at only a few microamp. or milliamp. The advantage of the high voltage consists in a rapid and intensive ionization of the particles, odorous substances or bacteria contained in the air. In this way, the time that the air is exposed to the electric field can be greatly reduced which, in addition to achieving the highest possible separation, permits a very compact design of the apparatus.

It is known that germs and bacteriaare killed by a sufficient exposure to an electric field. Although the duration of exposure of the bacteria-infected air in the apparatus described herein-has been reduced to only one second, experiments by experts in hospitals and laboratories have proved that the air was sterilized by a single pass through the apparatus. The favorable results of this apparatus are achieved by the combination of ionization, high voltages, oxidation through ozone, and immediate separation in a steady flow of water film. However, in order to attain a strong, precise ionization without enriching the purified air with ozone produced on glow discharge, it is necessary to design the electrode in a particular form. The electrode is connected to a high voltage direct cur-rent source and is suspended in a duct-through which air is drawn by any conventional means, for example in a fan. At one end of the electrode, preferably adjacent to the inlet opening of the duct, the electrode is provided with spaced fins having serrated edges which face laterally in opposite directions towards walls of the duct. The duct walls are covered with a continuous liquid flow (herein referred to as a separator electrode). The toothlike projections (herein referred to as spray electrodes of each serrated edge are staggered vertically and thus produce a strong ionization with spray discharge. The impurities contained in the passing air are not only ionized, but also oxidized through the ozone generated during the corona.

The second part of the electrode consists of a smooth plate of the same polarity as the spray electrodes. The distance to the separator electrode however is here smaller. Thus, ozone is not produced in the second part of the apparatus, and the ozone produced at the initial part of the electrode is absorbed into the water. The water ionized in this manner remains free from germs and odors.

In order to prevent any escape of ozone as a possible result of supersaturation of the water, there is additionally installed a filter of active carbon between the electrode and the fan adjacent tothe outlet of the shaft, which filter absorbs the last remaining residue of possibly accruing ozone. An electric filter is preferably su- FIG. 1 is a schematic illustration in vertical elevation of one embodiment of the invention;

FIG. 2 is an elevational view of the electrode shown in FIG. 1;

FIG. 3 is a bottom view of the electrode shown in FIGS. 1 and 2;

FIGS. 4 and 5 are schematic elevational views of a1- temate embodiments of the invention; and,

FIG. 6 is an elevational view of a modified electrode.

Referring now to FIG. 1, there is shown one embodiment of the invention having a fan 1 which draws air into the duct d through an inlet opening 2. An electrode generally indicated at e is suspended by means of an insulator 7 in the duct d. The air is drawn past both sides of the electrode as schematically depicted by the flow arrows in the drawing.

The walls W and W of the duct d are covered by a flow of liquid 4 which originates at discharge conduits 6 and flows downwardly to reservoir 9. As mentioned above, the liquid flow serves as and is herein referred to as a separator electrode.

With further reference to FIGS. 2 and 3, it will be seen that the electrode e is provided with a lowersection 3 made up of vertically spaced plates p p each of which is provided with laterally disposed serrated edges forming tooth-like projections typically referred to at t. As is best shown in FIG. 3, the plates are arranged such that the projections t are vertically staggered. The upper part 5 of the electrode e is made up of smooth plates 50. The electrode e is connected by conventional means conductor to a high voltage direct current generator 8. As the air is drawn past the lower section 3 of electrode e, the particles and impurities suspended therein are ionized and oxidized and driven into the liquid films 4. Whatever particles remain in the air are next acted upon by the second section 5 of the electrode, which is designed to intensify the electric field. The particles which are driven into the liquid films 4 are washed into the reservoir 9 which may either empty into a sewer, or which may be filtered and recirculated through the apparatus. An electrical resistance heating element 10 may be installed adjacent to the outlet of duct d for the purpose of heating the purified air.

FIG. 4 shows another embodiment of the apparatus which may be adapted either for stationary or mobile use. Here, the electrode e is generally U-shaped, with each leg forming the separate electrode sections 3 and 5. The section 3 adjacent to the entrance opening 2 of the apparatus is again provided with vertically spaced plates typically indicated at p, each of which is pro vided with a serrated edge like that shown in FIG. 3 facing the duct wall w,. The other section 5 of the electrode is comprised of an elongated flat plate 5a laterally spaced from duct wall w,. A fan 1 again draws air through the U-shaped duct d. The walls w, and W2 of the duct are again covered by a liquid flow 4 which originates at outlets 6 and which flows downwardly to a reservoir 7. The liquid in reservoir 9, usually water, may be heated by a heater 12 if it is desired to increase the humidity of the air being processed.

FIG. shows another embodiment of the invention which may be employed as a hood located over kitchen ovens, work benches, etc. Here again air is drawn upwardly by means of a fan 1 through a duct d, the latter communicating with a plurality of inlet openings 2 located in a double floor beneath reservoir 9. The elec-v trode e is provided with two sections 3 and S'substantially identical in design to that previously described in connection with FIGS. 1-3. A pump 15 is connected by conventional conduit means 22 to both the reservoir 9 and the discharge nozzles 6, the latter serving to produce a downward flow 4 of liquid along conduit walls W and W back to reservoir 9. An active carbon filter 13 is provided in conduit d between electrode e and fan 1 for the absorption of ozone residues. Means schematically indicated at 17 may also be employed to add chemicals to the water for the purpose of perfuming or disinfecting the same. Removable plates 14 are provided in order to lengthen the hood for certain applications, as for example when the apparatus is employed over a work bench where gases or vapors are being produced by welding or soldering.

FIG. 6 shows an electrode e which is covered with insulating elements 16 and 17 serving as guides for the incoming air to prevent it from being pushed or repelled by the so-called electric wind" that is created by high voltages.

I claim:

1. Apparatus for filtering air comprising in combination: a duct having an inlet opening at one end and an outlet opening at the other end, the said duct having spaced opposed walls; means for causing liquid to flow over said walls; means in said duct for causing a flow of air therethrough; electrode means suspended in said duct between said walls, said electrode means being divided into a first section adjacent to said inlet opening and a second section adjacent-to said outlet opening, said first section having a plurality of spaced plates extending transversally to the flow of air through said duct and said second section having flat plates extending parallel to the flow of air through said duct; and a high-voltage direct current generating means connected to said electrode.

2. The apparatus as claimed in claim 1 wherein the said generating means generates an operating current of between 20 and KV direct current.

3. The apparatus as claimed in claim 2 further characterized by an active carbon filter in said duct between said electrode means and said outlet opening.

4. Apparatus according to claim 1 wherein both said duct and said electrode means are provided with generally U-shaped configurations.

5. Apparatus according to claim 1 wherein the said liquid is water, and wherein there is provided means for heating the water in order to increase the moistening of the air passing through said duct.

6. Apparatus according to claim 1 wherein there is provided means for injecting chemicals into the liquid being caused to flow over said walls, the said chemicals being operative to perfume or disinfect the liquid. 

1. Apparatus for filtering air comprising in combination: a duct having an inlet opening at one end and an outlet opening at the other end, the said duct having spaced opposed walls; means for causing liquid to flow over said walls; means in said duct for causing a flow of air therethrough; electrode means suspended in said duct between said walls, said electrode means being divided into a first section adjacent to said inlet opening and a second section adjacent to said outlet opening, said first section having a plurality of spaced plates extending transversally to the flow of air through said duct and said second section having flat plates extending parallel to the flow of air through said duct; and a high-voltage direct current generating means connected to said electrode.
 2. The apparatus as claimed in claim 1 wherein the said generating means generates an operating current of between 20 and 100 KV direct current.
 3. The apparatus as claimed in claim 2 further characterized by an active carbon filter in said duct between said electrode means and said outlet opening.
 4. Apparatus according to claim 1 wherein both said duct and said electrode means are provided with generally U-shaped configurations.
 5. Apparatus according to claim 1 wherein the said liquid is water, and wherein there is provided means for heating the water in order to increase the moistening of the air passing through said duct.
 6. Apparatus according to claim 1 wherein there is provided means for injecting chemicals into the liquid being caused to flow over said walls, the said chemicals being operative to perfume or disinfect the liquid. 